This invention relates to arrangements for bearings containing rolling elements such as balls in which vibration is inhibited.
Rolling element bearings consist of an inner raceway, an outer raceway and an array of rolling elements such as balls held captive by a retainer between the two raceways to permit relatively friction free rotational motion of one raceway with respect to the other. In operation the components of a rolling element bearing are subject to wear, leading to increased vibration levels which can cause mechanical failure. In the present state of the art rolling element bearings are replaced when the vibration level indicates that the probability of imminent mechanical failure is increasing.
The sources of damaging vibration in a rolling element bearing include the shape of the raceway, the natural frequency of the raceway, the shape of the rolling elements, the amount of bearing pre-load, instability of a rolling element retainer, and contamination of the contact surfaces of the rolling elements and the raceways. Replacement of bearings requires an interruption of operation of the related equipment and an increased frequency of bearing replacements reduces plant efficiency.
The Okada et al. U.S. Pat. No. 5,975,764 discloses a bearing arrangement having an outer raceway covered by an insulating elastic material to inhibit electric corrosion between the rolling elements and the inner or outer raceway as a result of potentials which can be induced in them when they are installed in an electric motor.
The Mizutani et al. U.S. Pat. No. 5,375,933 also discloses a bearing arrangement in which an insulating coating, which may be made of a resin material containing glass fibers to provide creep resistance, is applied to the outer surfaces of the bearing.
In the Larson et al. U.S. Pat. No. 5,845,998, a ball bearing has a metal annular outer raceway surrounded by a polymer outer bearing ring produced by injection molding of polymer material which is, in turn, retained within a metal housing.
The Kondo et al. U.S. Pat. No. 5,605,401 discloses a bearing arrangement having an outer ring formed of a resin material which may contain graphite.
None of the prior art discloses a bearing arrangement in which vibration is effectively inhibited to increase the life of the bearing.
Accordingly, it is an object of the present invention to provide a rolling element bearing arrangement which overcomes disadvantages of the prior art.
Another object of the invention is to provide a rolling element bearing arrangement which is effective to inhibit vibration of bearing components in a simple and economic manner.
These and other objects of the invention are attained by providing a rolling element bearing arrangement in which an outer raceway is provided with an outer ring of material which is effective to damp vibrations of the outer raceway. In one embodiment, the vibration damping ring includes a layer of resilient material and in another embodiment the vibration damping ring includes a heavy metal component. Preferably, the vibration damping ring is held against the outer race by an outer wrap of composite material. In addition, the bearing arrangement includes a rolling element retainer and stabilizer to apply a lateral stabilizing force to the rolling element retainer.